Back in 2015, two Georgia parents were charged with killing their 10-week old daughter. Reports state they watered down their daughter's breast milk, which caused electrolyte and sodium levels to drop causing her brain to swell.

Pediatric intensive care doctor at Sacred Heart, Dr. Jason Foland, calls it water poisoning. He said it is a rare, but they do see cases at the Sacred Heart, about a dozen per year.

"In a 1-month-old, two ounces can be enough to cause problems, four ounces can cause coma and death," he explained.

Dr. Foland said it's more common in summer months because people often think their baby needs water because it's hot outside. He also said they see cases where parents are trying to save money on formula and they don't realize the dangers of diluting it.

"The other most common thing is when parents run out of formula and want to soothe a crying baby so they dilute out their formula to make it last longer."

But how can something that's supposed to be good for you do the opposite in a baby?

He said, "A baby is smaller and has a different amount of body water percentage compared to older people. So they are more affected by taking water in, also because they are more young and more immature, their organs don't work as well. If they drink too much water, they can have trouble getting rid of that water."

Dr. Foland said babies can start drinking water when they are about six months old. The rule is about one ounce per month of age over a 24-hour period.